1. Field
This invention relates to uniform fluid transfer devices. It is particularly directed to industrial scale fluid transfer systems. It is used in columns or cells constituting a portion of chromatographic, ion-exchange, absorption, separation or distillation process systems.
2. State of the Art
Performance design criteria have evolved in connection with large scale process systems incorporating fluid transfer systems (those with columns or cells having diameters of two feet or larger) as follows:
(1) An ideal uniform distribution of fluid across the distributor or collector device should be approximated as closely as possible. The term "ideal uniform distribution" is intended to designate that a cross section of a flowing fluid of arbitrarily small thickness is taken normal to the flow direction through a column or cell and is mapped to a second similar cross section such that any point on the second cross section maintains the same relative position and relative velocity with respect to all other surface points observed before the mapping. Further, "ideal uniform distribution" is intended to designate that the cross section does not mix with any adjacent surfaces during the mapping.
2) In some process systems using uniform fluid transfer devices, a transition from turbulent to laminar flow occurs. For example, a fluid passing through a small diameter pipe at high velocity experiences turbulent flow. When such a fluid enters a large diameter cell, its velocity decreases, resulting in laminar flow. In a chromatography process, a laminar flow within a resin-filled cell is desired. The transition from turbulent to laminar flow conditions has often subjected a fluid to mixing conditions immediately upon exiting of the fluid from high flow velocity distributor orifices. Such mixing is considered to be undesirable, but it can be avoided through ideal uniform distribution
(3) Distributor layouts are generally difficult to configure so as to obtain an ideal uniform distribution on a circular surface. However, because industrial scale processes typically involve cylindrical vessels, i.e. have a cylindrical wall and circular inlet and outlet ends, a distributor layout must be useful in such vessels for practical application.
(4) The distribution and collection systems should both be conducive to plug flow of fluid through solid phase media, such as is common to chromatographic or ion-exchange applications.
(5) The composition of fluids flowing in some processes alternates between two or more liquid phases. For example, a feed stock and eluate may be present, and often a raffinate or other phase is also present. The distribution and collection systems should maintain a well-defined interface between the various liquid phases flowing through the system. Discrete phases should be kept separate by maintaining plug flow characteristics. "Plug flow" implies that respective liquid interfaces of a phase plug reach, respectively and approximately simultaneously, the inlet of the distributor closest to the source and an outlet remote from that source. The same principle applies to the collection system.
(6) For systems containing a solid phase, e.g., chromatography or ion exchange systems, it is desirable to minimize the void between a distributor (or collector) and the surface of the solid phase, thereby reducing the opportunity for back mixing. Any orifice or nozzle system functioning as a distributor and/or collector should be in contact with, or at least in near proximity to, the surface of the solid medium at all times. Structure associated with these elements should desirably provide a barrier against which the solid medium can be packed.
(7) For purposes of practical industrial application, the design of the distributor used should be easy to scale to any desired size.
Various separator systems using distributor/collector systems are disclosed by U.S. Pat. Nos. 2,985,599; 4,001,133; 4,182,633; 4,412,866 and 4,999,102, the disclosures of which are incorporated by reference for their teachings concerning the operation and control of separator systems generally and for their illustrations of various structures and mechanisms relied upon in the separation art for distributing liquids to an interface or collecting liquids from an interface. U.S. Pat. No. 4,412,866 is generally instructive, and FIG. 2 of that patent discloses representative distributor and collector devices. U.S. Patent No. 4,999,102 also discloses distributor and collector systems suitable for use with other apparatus of separator systems for various processes.
U.S. Pat. Nos. 4,537,217 and 4,636,315 disclose small scale fluid distributors formed from solid bodies, such as tiles, with entry openings on one surface and a plurality of distribution openings on the opposite surface corresponding to each entry opening. The entry openings are connected to the distribution openings by internal channels and bores.
As used herein and in the appended claims: The term "fluid system" is intended to designate the apparatus of any unit operation, including those specially identified by this disclosure, in which liquid is either introduced to or withdrawn from a cell at a zone approximately transverse the direction of flow through the cell. The term "cell" is intended to include the terms "vessel" and "column", as well as any other structure utilized by practitioners of the separation arts, to effect a separation and/or extraction of components from an admixture by bringing the admixture into contact with solid or liquid exchange media. "Cross-sectional zone" (or region) refers to a region within a cell bounded by cross sections of the cell oriented transverse (typically approximately normal) the longitudinal direction of flow through the cell. "Longitudinal direction of flow" refers to the direction of flow from an inlet towards an outlet within a cell. "Longitudinal" is used consistently to designate the dominant flow path of fluid through a cell without regard to direction. "Hydraulically identical", as applied to conduits, plenums and the like, means that the elements compared react to pressure differentials in a fluid circuit as though they were structurally identical. "Distributor" (or "distribution system") refers to structure through which fluids are introduced to a cell and "collection" or (collection system") refers to structure used to withdraw fluids from a cell, in each instance from a cross-sectional zone. The term "plenum" is defined in this application as a fluid flow device which receives fluid from a single inlet conduit and discharges the fluid into a plurality of outlet conduits, or receives fluid from a plurality of inlet conduits and discharges it into a single outlet conduit.